Light strings having lights connected electrically in a series are well known especially around the holidays when such light strings are used for decorative purposes. Generally, the lights in the string are electrically in series rather than in parallel. One particular drawback to these types of light strings is that when a light bulb is removed from the socket, the entire series is rendered inoperable. Each light bulb within its respective socket completes the electrical circuit so when a light bulb is removed or the filament burns out within the light bulb, a gap is created in the circuit and electricity is unable to continue to flow through the circuit. When a "good" light bulb is inserted into the socket, it completes the circuit, thus allowing electricity to flow uninterrupted.
One solution that allows the circuit to continue to function without a light bulb being in the socket is found in U.S. Pat. No. 5,453,664, issued to Harris and entitled "Light String With Improved Shunt System". The Harris patent is directed to a bulb shunt system that is configured to shunt the electric current passing through the light bulbs if a filament breaks or is removed from the socket.
The Harris system has a first shunt located inside the glass envelope of the light and a second shunt is located either in the lamp holder or in the socket. The combined resistance of the shunts is greater than the resistance of the light bulb therefore allowing the string to remain lit.
While the Harris device allows for the electrical current to continue if a light bulb is damaged and remains within the socket or if the light bulb is completely removed from the string of lights, it requires special light bulbs designed to include the first of the two shunts. This system also requires a second shunt system to be made within the socket, therefore creating an extra shunt to be present in every socket/light bulb combination. That is, only one shunt is utilized at a time and an extra or excess shunt is present in every lamp. Moreover, when a bulb is remove, such as when it has been burned out, without turning out the light, the shunt welds and thereby prevents the replacement bulb from lighting. Finally, as each socket's shunt welds, the voltage across the remaining lamps increases, thereby reducing the life of these bulbs, and causing a cascading of bulb breakdowns.
While the above stated devices are a fair representation of the current prior art, there remains room for improvement as defined by the currently claimed invention.